1. Field of the Invention
The present invention relates to a configuration of an electronic endoscope apparatus capable of outputting pictures of an object to be picked up, into a high-definition television system monitor particularly in an environment where various types of electronic endoscopes having different numbers of pixels of a solid-state pickup element can be used.
2. Description of the Related Art
An electronic endoscope apparatus has a CCD (Charge Coupled Device), etc., which is a solid-state pickup element, incorporated at a distal end of an electronic endoscope (electroscope), and the CCD picks up an object to be picked up, on the basis of illumination brought about by a light source unit. And, picked-up signals obtained by the CCD of the electronic endoscope are outputted to a processor unit, wherein the picked-up signals are subjected to a picture process by the processor unit, pictures of the object to be picked up are displayed on a display monitor, and still pictures are recorded in a recording unit.
Generally, it is in an attempt that, although pictures of the object to be picked up in a display monitor of the NTSC system (the aspect ratio 3:4) which is the standard television system, the pictures are displayed in a display monitor of a high-definition (HDTV) system (the number of scanning lines of which is increased to be approximately double) of higher grade (the aspect ratio 9:16) as shown in, for example, Japanese Published Unexamined Patent Application No. H4-253830. Since, in an electronic endoscope apparatus, normal NTSC system signals (analog signals) are generated from output signals of a CCD, the NTSC signals are converted to high-definition signals.
On the other hand, still pictures (digital signals) of an object to be picked up, which are obtained by an electronic endoscope apparatus, are recorded in a video recording unit and a filing apparatus (recording medium) based on a personal computer, etc. Thereafter, the still pictures are displayed in a television monitor and a personal computer monitor for observation. A CCD based on a higher number of pixels, which can bring about high-resolution power, has been employed.
As described above, since the CCD which is a solid-state pickup element has recently been upgraded in resolution power and pixel number, in picture display based on the high-definition television system, there is an advantage in that it is impossible to observe an object to be picked up, the image quality of which has been improved in comparison with prior arts, even in picture display based on the high-definition television system. However, as described above, in the case of converting NTSC signals to high-definition television signals, the high-definition television signals are restricted by the resolution power of the NTSC picture signals, wherein there is a problem in that the CCD resolution power upgraded in quality cannot be sufficiently utilized.
In addition, since CCDs having different pixel numbers are incorporated, as described above, in an electronic endoscope, it is useless or wasteful in terms of costs that converting circuits to high-definition television signals are disposed, or renewed (or replaced) in a processor unit in response to differences in the CCD pixel number and change in upgrading the pixel number, and the apparatus becomes expensive.
Further, as regards equipment used in medical fields, strict standards are requested in regard to EMC (Electro-Magnetic Compatibility) and electrical safety, and it is unrealistic that the above-described medical standards are satisfied in large equipment such as a personal computer in order to convert signals to high-definition television signals.
Also, when converting pictures obtained by an electronic endoscope apparatus to the high-definition television system and observing the same, it is requested that the pictures are video-recorded and stored in a high-definition television recording unit. In this case, it becomes necessary to transmit control signals (commencement and stop of vide-recording and storing etc.) from an electronic endoscope side to a recording unit. Moreover, intransmission of control signals for recording, it is requested that the transmission system is composed of as few a number of transmission lines as possible in view of simplification of the structure and electrical safety.